Melt adhesive compositions

Abstract

 A melt adhesive composition containing an amorphous polypropylene, a selectively hydrogenated monoalkenyl arene/conjugated diene block copolymer and a tackifier.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] This invention relates to melt adhesive compositions especially useful in adhering polyolefin bodies to themselves, to other polyolefin bodies and to other non-polyolefinic bodies comprising a blend of (1) an amorphous polypropylene (amorphous polyalphaolefins), (2) a selectively hydrogenated monoalkenyl arene/conjugated diene block copolymer of linear or radial configuration and (3) a tackifier.

2. Description of the Prior Art

[0002] The preparation of adhesives containing amorphous polypropylene and block copolymers containing unsaturated mid block copolymers, for example, polystyrene-polybutadiene-polystyrene (S-B-S) or polystyrene-polyisoprene-polystyrene (S-I-S), tackifier and a rubber-extending oil is known, as evidenced, for example, in U.S. Patent No. 3,862,068 to Russell. Such adhesives have limited elevated temperature melt stability, limited resistance to O₂ and UV, but, most important, exhibit limited performance characteristics on untreated polyolefin surfaces wherein high bond integrity and durability are also required. U.S. Patent No. 3,686,107 to Russsell also discloses similar compositions having similarly undesired characteristics noted above. St. Clair et al in U.S. Patent No. 4,296,008 prepares a sealant composition containing a selectively hydrogenated S-B-S and S-I-S block copolymer in combination with tackifying resins, plasticizers and solvents. U.S. Patent No. 4,138,378 to Doss also discloses a sealant formulation containing selectively hydrogenated block copolymers, a polyalkene plasticizer, a tackifying resin and a filler. St. Clair et al in U.S. Patent No. 4,286,077 disclose the use of selectively hydrogenated block copolymers in combination with a tackifier and a plasticizer to obtain a pressure sensitive adhesive. Additional variants in adhesive preparations involving the use of hydrogenated block copolymers are described in U.S. Patent No. 4,151,057 to St. Clair et al.

[0003] The patents discussed above are examplary of the prior art involving the utilization of various types of block copolymers in the preparation of adhesives and sealants. Obviously, none of these references discloses the use of an amorphous polypropylene in combination with selectively hydrogenated monoalkenyl arene/conjugated diene block copolymers and tackifiers. We have discovered that such combinations containing an amorphous polypropylene exhibit excellent adhesivity to untreated polyolefins and are useful in various plastic fabrication and assemblies involving such surfaces.

SUMMARY OF THE INVENTION

[0004] We have found that when a selectively hydrogenated monoalkenyl arene/conjugated diene block copolymer, such as a selectively hydrogenated styrene-butadiene-styrene or styrene-isoprene-styrene copolymer, is combined with an amorphous polypropylene and a tackifier, the resultant adhesive exhibits an unexpected and superior adhesivity to polyolefin surfaces, such as polyethylene and polypropylene. These adhesives have a special utility in the fabrication of a variety of articles, for example, in the preparation of packaging films, closures or wax-coated paper or paperboard boxes, assembly of injection molded objects and containers, some or all of which will require the necessity for an adhesive use to provide the desired fabricated products for various articles of commerce. Thus, it is absolutely necessary that the adhesive used exhibit excellent adhesivity to such surfaces to hold the assemblies together through their lifetime of use. Our present adhesives, moreover, have an excellent affinity to untreated polyolefin surfaces. It is well known in the art that polyolefins can be rendered adhesive receptive only after appropriate surface treatment is employed, such as via the use of corona discharge, flame or via plasma. Such approach will obviously require an additional step to impart surface bondability to polyolefins, and hence, any approach to the design of an adhesive which will overcome this additional, and costly, step, that is, exhibit a direct affinity to untreated polyolefin surfaces, will be of much interest and useful to industry.

[0005] The amorphous (atactic) polypropylenes, including amorphous polyalphaolefins, and combinations thereof, used herein to prepare the novel melt adhesive compositions claimed herein will show varying extent of solubility in hydrocarbon solvents, such as pentene, hexane, etc., have a crystallinity of less than about 10 weight per cent, preferably less than about five weight percent and possess a molecular weight in the range of about 300 to about 50,000, preferably about 1000 to about 25,000. The method used in preparing the amorphous polypropylene or amorphous polyalphaolefins and recovering the same, has no effect on its utilization in the preparation of the novel melt adhesive claimed herein. Thus, amorphous polypropylene formed as a byproduct in minor amounts during the production of crystalline polypropylene (homo or copolymer resins) by the polymerization of propylene in the presence of stereospecific catalysts by processes disclosed, for example, in U.S. Patents Nos. 3,679,775 to Hagemeyer et al, 3,529,037 also to Hagemeyer et al and 3,900,694 to Jurrens can be used. On the other hand amorphous polypropylene (amorphous polyalphaolefins) produced directly, that is, by intent, without the production of crystalline copolymers of propylene and lower olefins, as disclosed, for example, in U.S. Patents Nos. 3,923,758 to Carter et al, 3,954,697 to McConnell et al, 4,072,812 to McConnell et al, 4,072,813 to McConnell et al, 4,259,470 to Trotter et al, 4,309,522 to Dietrich et al and 4,317,897 to Herrmann et al can also be used. While the amorphous polypropylenes (amorphous polyalphaolefins) used herein can be homopolymers of propylene, it is within the purview of our invention to use substantially amorphous products based on propylene copolymerized with olefins, such as ethylene, butene, pentene, hexene, nonene, decene, etc., whether such products have been obtained intentionally or as by-products. The latter copolymers are defined herein as "amorphous polyalphaolefins". In the claimed invention herein, the term "amorphous polypropylene" is intended to include the said "amorphous polyalphaolefins". Such amorphous copolymers can have a melt viscosity in the range of about 200 to about 50,000, or even higher, cps at 375°F (190.5°C) (ASTM D 3236). These copolymers will contain propylene in an amount ranging from about 25 to about 99.5, or even higher, weight percent, generally from about 50 to about 99.5, or even higher, weight percent, with the remainder being one or more of the other olefins identified above. The amorphous polyalphaolefins useful herein are further described, for example, in U.S. Patents Nos. 4,022,728 to Trotter et al, 4,120,916 to Meyer et al, 4,210,570 to Trotter et al, 4,264,756 to Trotter et al and 4,288,358 to Trotter et al.

[0006] The block copolymer used herein to prepare the novel melt adhesive composition claimed herein can be either a multiblock copolymer containing the structure A-B, the structure A-B-A₁ or the radial structure (A-B)_xY, or combinations thereof, wherein A and A₁, the same or different, are alkenyl arene polymer blocks, preferably monoalkenyl arene polymer blocks, B is a block containing a hydrogenated conjugated diene polymer, preferably a block consisting essentially of a hydrogenated conjugated diene polymer, Y represents a residue of a polyfunctional coupling agent or a polyfunctional initiator and x is a number having a value greater than 2, preferably from 3 to 4. The geometrical structure of the block copolymers used herein is not critical, as long as the A, A₁ and B components thereof fall within the above definition, and therefore the structure can be either linear (including tapered), radial or branched. Each of the blocks A, A₁ and B can be substantially homopolymer or random copolymer blocks, as long as at least about 80 weight percent, preferably at least about 75 weight percent of each block predominates in at least one class of the monomers characterizing the blocks and the A and A₁ blocks individually predominate in alkenyl arenes and Block B individually predominates in a hydrogenated conjugated diene.

[0007] The term "alkenyl arene" can be any alkenyl arene having from 8 to 18 carbon atoms, preferably from 8 to 9 carbon atoms, and can include styrene itself and its analogs and homologs, for example, alpha methyl styrene and ring-substituted styrene, such as, ring alkylated styrenes, for example, 3-methyl styrene, 4-methyl styrene, 4-n-propyl styrene, and other alkenyl arenes, such as 1-vinyl naphthalene, 2-vinyl naphthalene and the like. Styrene and alpha methyl styrene are preferred, with styrene being especially preferred.

[0008] The term "conjugated diene" is intended to include a conjugated diene having from 4 to 8 carbon atoms, preferably from 4 to 6 carbon atoms, such as 1,3-butadiene, isoprene, 1,3-pentadiene, 2,4-hexadiene, 3-ethyl-1,3-pentadiene and the like and copolymers of such conjugated dienes, provided that such copolymer is characterized by such conjugated diene and such copolymer contains at least about 50 weight percent, preferably at least about 75 weight percent, of such conjugated diene. When the block copolymers defined above, A-B-A₁, A-B or (A-B)_xY, are selectively hydrogenated, for example following the procedure defined in U.S. Patents Nos. 3,595,942 to Wald et al and 3,696,088 to DeVault, blocks A and A₁ are substantially unaffected by the hydrogenation but at least about 75 weight percent, generally all, of the conjugated diene polymer in block B is converted to the corresponding hydrogenated species. Thus, when the block B is composed of polybutadiene the resulting block is, or at least appears to be, a copolymer of ethylene and butene-1 (EB). When block B is composed of isoprene, the resulting block is, or at least appears to be, a copolymer of ethylene and propylene (EP).

[0009] Typical block copolymers that can be used include the following:

(1) polystyrene-hydrogenated polybutadiene-polystyrene,

(2) polystyrene-hydrogenated polyisoprene-polystyrene,

(3) poly(alphamethyl) styrene-hydrogenated polybutadiene-poly(alphamethyl) styrene,

(4) poly(alphamethyl) styrene-hydrogenated polyisoprene-poly(alphamethyl) styrene,

(5) polystyrene-hydrogenated polybutadiene,

(6) polystyrene-hydrogenated polyisoprene,

(7) poly(alphamethyl) styrene-hydrogenated polybutadiene,

(8) poly(alphamethyl) styrene-hydrogenated polyisoprene,

(9) polymers of the configuration (A-B)_xY, wherein A represents polystyrene or poly(alphamethyl) styrene segments, B represents a hydrogenated polybutadiene or polyisoprene segment, Y represents a residue of a polyfunctional coupling agent or a polyfunctional initiator and x is a number having a value greater than 2, preferably from 3 to 4,

(10) combinations of the above in various proportions, etc.

[0010] The average molecular weight of the individual polymer blocks A, A₁ and B can vary over a wide range. The total average molecular weight of the alkenyl arene blocks can be in the range of about 2000 to about 125,000, but preferably will be in the range of about 5,000 to about 50,000. The selectively hydrogenated conjugated diene polymer block will have an average molecular weight in the range of about 10,000 to about 500,000 but preferably will be in the range of about 20,000 to about 300,000. The block copolymers used herein will contain a total from about five to about 50 weight percent of the alkenyl arene block(s), preferably from about 10 to about 35 weight percent.

[0011] Examples of the block copolymers that can be used herein are further defined in U.S. Patents Nos. 4,151,057, 4,286,077 and 4,296,008 to St. Clair et al, and in U.S. Patent No. 4,138,378 to Doss discussed hereinabove.

[0012] The third necessary component in preparing the novel melt adhesive compositions claimed herein is a hydrocarbon tackifier. Suitable for such use can be any hydrocarbon tackifier, or combinations thereof, generally used, or suitable for use, in the preparation of hot melt adhesives. A particularly suitable tackifier can be obtained from commercially available hydrocarbon resins resulting from the polymerization of monomers consisting of olefins, cycloolefins and diolefins, for example, residual byproduct monomers resulting from the manufacture of isoprene. Such tackifiers are described, for example, in U.S. Patent Nos. 3,932,330 to Lakshmanan, 4,022,728 to Trotter et al and 4,072,735 to Ardemagni. Such petroleum-derived hydrocarbon resins are sometimes also referred to as synthetic terpene resins. Other types of tackifiers also suitable for use herein include products obtained from cyclopentadiene and dicyclopentadiene polymerization and subsequent hydrogenation, conventional terpene resins and modified terpene resins obtained as a result of the polymerization of such terpene-derived monomers, such as alpha- and beta-pinene, dipentene and limonene, rosin and rosin esters, hydrogenated rosin products and disproportionated rosin products. Petroleum hydrocarbon resins that have been post hydrogenated to yield a more thermally stable resin are especially preferred. The tackifiers used to prepare the novel melt adhesive compositions claimed herein will typically exhibit a ring and ball softening point (ASTM E 28) in the range of about 10^o to about 150^o, preferably about 25^o to about 125^oC.

[0013] The three components required to obtain the novel melt adhesives claimed herein can be present in the amounts defined below in Table I.

TABLE I

	Weight Percent
	Broad Range	Preferred Range
(1) Amorphous Polypropylene	5 - 95	30-90
(2) Selectively Hydrogenated Block Copolymer	2.5 - 40	5-20
(3) Hydrocarbon Tackifier	2.5 - 55	5-50

[0014] In an embodiment herein our melt adhesives can have also incorporated therein isotactic polypropylene, ethylene-propylene copolymers, homo and copolymers from butene-1, paraffin and microcrystalline waxes, Fischer-Tropsch waxes, low molecular weight polybutenes, polyisobutylene, low molecular weight (700 to 25,000) polyethylene, conventional low density polyethylene, process oils, etc., in an amount upto about 40 weight percent, generally upto about 25 weight percent, based on the final adhesive composition.

[0015] Since hot melt adhesives tend to experience varying degrees of thermal exposure during thermal processing and/or during application to the substrate, it is desirable to incorporate therein one or more antioxidants in small amounts to inhibit thermal and/or thermoxidative degradation. Several types of commercial products, predominantly of the hindered phenol types, are available for this purpose to function as primary antioxidants. A secondary antioxidant belonging to the general classification of thioesters and phosphites can also be used in combination with the hindered phenols. Exemplary of antioxidants suitable for use herein include tetrakis[methylene 3-(3′,5′-di-t-butyl-4-hydroxyphenyl) propionate] methane;
2,2′-ethyldenebis(4,6-di-tertiary-butylphenol);
1,1-3-tris(2-methyl-4-hydroxy-5-t-butyl phenyl) butane; and 1,3,5-trimethyl-2,4,6-tris(3,5-tertiary-butyl-4-hydroxybenzy­l) benzene. Secondary antioxidants, such as dilauryithiodipropionate; pentaerythritol tetrakis(beta-laurylthiopropionate) and various alkyl-, aryl-, di- and polyphosphites and thiophosphites can also be employed in combination with appropriate hindered phenols. Effective amounts of antioxidants that can be used can range from about 0.05 to about five weight percent, preferably from about 0.1 to about 2.5 weight percent, based on the weight of the final adhesive composition.

[0016] The preparation of the novel melt adhesive claimed herein is not critical and any suitable method can be employed. In a preferred embodiment a mixing vessel is heated to an elevated temperature, for example in the range of about 350^o to about 400^oF (162.8^o to 204.5^oC) and the amorphous polypropylene, tackifier and the antioxidant, if used, are added thereto. The resulting mixture is allowed to soften under slow mixing to homogeniety. At this juncture the block copolymer is added in small quantities to the melt with continued mixing until the entire amount is added. Following this mixing is further continued with homogeniety of the entire adhesive mass occurs. After this the product is collected in a release line tray. The total mixing time is generally in the range of about two to about four hours.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0017] The present invention relating to the novel hot melt adhesives claimed herein can further be illustrated by the following. A number of compositions were prepared either using an oil-heated Brabender mixing vessel having a compounding bowl with a capacity of 450 milliliters or using a stainless steel beaker heated with a GLAS-COL mantle with a capacity of 500 milliliters. Before beginning, the Brabender mixing vessel was heated to a temperature ranging from 350^oF (176.7^oC) to 380^oF (193.3^oC). The amorphous polypropylene, tackifier and antioxidant were allowed to soften and were mixed at such temperature under slow mixing for 30 minutes. When the preparation was carried out in a stainless steel beaker, sufficient amount of the amorphous polypropylene and tackifier, along with sufficient antioxidant, were placed in the container and the entire mass was slowly heated to the desired temperature. At the point of fluidity of the melt, slow stirring commenced to bring the mass to homogeneity. In both mixing approaches following homogenization, the block copolymer was slowly added in small quantities under continuous mixing until the desired homogeneity of the mixture was obtained. Total mixing time ranged from about two to about four hours. The mixed compositions were then collected on a release line tray.

[0018] The thermal stabilities of the adhesive compositions that were prepared were determined by exposing 8 to 10 grams quantities of a sample in a five-inch x one-inch test tube to a temperature environment of 350^oF (176.7^oC) for 24 hours. At the end of the 24 hours, the composition was visually observed for any separation stratification and loss in composition homogeneity. The ring and ball softening points of the compositions were determined according to ASTM Procedure E-28. The melt viscosities of the compositions were determined according to ASTM Procedure D 3236. The Peel Adhesion Failure Temperature (PAFT) and Shear Adhesion Failure Temperature (SAFT) were performed according to TAPPI Procedure T814-77; and the peel strength values were determined according to ASTM Procedure D 1876.

[0019] A Slautterback "minisquirt" hot melt gun applicator was used to prepare the peel strength, 180^o reverse peel strength. PAFT and SAFT specimens to test the hot melt adhesive compositions of this invention. To determine peel strength values of these compositions, polyethylene laminated test specimens were prepared by applying the molten hot melt adhesive compositions at 350°F (176.7^oC) to a 4-mil (one-inch by six-inch) high density polyethylene film as a continuous strip one inch wide along the film of 2 1/2-inch length, and then another 4-mil high density polyethylene film of the same dimensions was placed on top of the film carrying the strip of the hot melt adhesive composition. Enough contact pressure was applied via a rubber roller to spread the adhesive and to bring the adhesive in intimate contact with the surfaces. The laminates were then aged for a minimum of 24 hours prior to testing. Three specimens for each composition were prepared and the bond strength was measured by peeling at the glue line by means of a J. J. Lloyd Tensile Tester at a peel rate of 50 millimeters per minute. The maximum force in grams necessary to cause rupture of the bond was noted. The average of the three such determinations was recorded.

[0020] To obtain the 180 degrees reverse peel strength values, three-mil Mylar film/180-mil high density polyethylene and three-mil Mylar film/120-mil polypropylene laminated test specimens were prepared by applying the molten hot melt adhesive composition at 350^oF (176.7C) to either 180 mil (one-inch by six-inch) high density polyethylene substrate or 120 mil (one-inch by six-inch) polypropylene substrate as a continuous strip one-inch wide along the substrate length and then a 3-mil (one-inch by 12-inch) strip of Mylar film was placed on top of the substrate carrying the strip of the hot melt adhesive composition. Three assemblies of each were prepared for each adhesive valuation. Following this procedure enough contact pressure was applied via a rubber roller to spread the adhesive evenly and to bring the adhesive in intimate contact with each of the surfaces. The laminates were then aged for 24 hours prior to testing. Testing procedures were the same as for the polyethylene specimens.

[0021] To determine Peel Adhesion Failure Temperature (PAFT) and Shear Adhesion Failure Temperature (SAFT) values of the hot melt adhesive compositions, 78 pound (one-inch by six-inch) kraft laminated test paper was used by applying each of the compositions to the kraft strip by means of a Slautterback "minisquirt" hot melt applicator. The hot melt adhesive compositions were applied at 350^oF (176.7^oC) to the kraft paper as a continuous coating of one-inch by 2 1/2-inch area of the kraft substrate for PAFT performance and of one-inch by one-inch areas of the kraft substrates for SAFT performance. Then another 78 pound kraft paper strip of the same dimension was placed on top or positioned longitudinally on a kraft paper carrying the coating of the hot melt adhesive compositions. Sufficient contact pressure was then applied to bring the adhesive into intimate contact with the surfaces. The laminates were then aged for 24 hours prior to testing. Two or three specimens for each composition were prepared. The test was carried out by exposing the assemblies in an oven conditioned at 100^oF (37.8^oC). The specimens were suspended at one end in the oven to a suitable device (a paper clip), while to the other end either a 100-gram load (PAFT) test) or a 500-gram load (SAFT test) were attached. From this point on, the temperature of the oven was increased programmatically at the rate of 10^oF (5.5^oC) every 15 minutes until the failure temperature was reached. The average failure temperature was then recorded.

[0022] The components used in the preparation of the adhesive compositions are identified below in Table II.

[0023] Data obtained in a series of runs are set forth below in Table III.

TABLE III

BASE RUNS
Run #	1	2	3	4	5	6	7	8
	PARTS BY WEIGHT, GRAMS
APP, K-TAC 100B	100.00	85.00	50.00	53.75	75.00	-	-	50.00
Shellwax 700	-	-	-	-	-	47.50	-	-
Kraton GX-1657	-	15.00	15.00	7.50	7.50	5.00	9.52	-
Escorez 5380	-	-	35.00	38.75	17.50	47.50	90.48	-
Wingtack 10	-	-	-	-	-	-	-	50.00
Isonox 129 / DLTDP (1:1)	0.60	0.6	0.60	0.60	0.60	0.60	0.60	0.60
Total	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6

Properties
Viscosity, cps @ 350°F	2000	10500	9350	3300	4300	40	1400	275
R&B,°C	154	156	139	149	152	89	93	142

Performance
Peel Strength, g/in, 50 mm/min
HDPE (4 mil)/ HDPE (4 mil)	950	1045	4400	3180	1630	No Adh	No Adh.	330
Mylar(3 mil)/PP (120 mil)	1500	160	4090	6240	2880	No Adh	No Adh.	363

[0024] An inspection of the data in Table III shows that when amorphous polypropylene is used alone as an adhesive in Run No. 1 some level of adhesion is obtained to high density polyethylene (HDPE) and polypropylene (PP) surfaces. When amorphous polypropylene was combined solely with a selectively hydrogenated block copolymer composed of styrene and ethylene butylene polymer blocks (Kraton GX-1657) in Run No. 2, no appreciable improvement in adhesion to a HDPE surface was achieved and adhesion to polypropylene was significantly reduced. When the same selectively hydrogenated block copolymer was combined solely with a tackifier in Run No. 7 no adhesion at all was obtained. When in Run No. 8 amorphous polypropylene was combined solely with a tackifier, the results were inferior to Run No. 1. The use of Kraton GX-1657, a wax and a tackifier, but no amorphous polypropylene, in Run No. 6 resulted in a composition exhibiting no adhesivity. Note, however, that in Runs Nos. 3, 4 and 5, wherein an adhesive containing the selectively hydrogenated block copolymer Kraton GX-1657, amorphous polypropylene and a tackifier was tested, unexpected and dramatic improvements in adhesive performance was obtained in both HDPE and PP surfaces.

[0025] An additional series of runs was made and the data obtained are set forth below in Table IV.

TABLE IV

Effect Of Component Levels On Blend Performance
RUN #	9	10	11	12	13	14
	PARTS BY WEIGHT, GRAMS
APP, K-TAC 100B	40.00	60.10	73.00	20.00	45.00	47.50
Kraton GX-1657	20.00	13.30	9.00	40.00	10.00	5.00
Escorez 5380	40.00	26.60	18.00	40.00	45.00	47.50
Isonox 129/ DLTDP (1:1)	0.60	0.60	0.60	0.60	0.60	0.60
Total	100.6	100.6	100.6	100.6	100.6	100.6

Properties
Viscosity, cps @ 350°F	14500	7500	4950	85500	3650	1650
R&B,°C	110	152	153	124	134	148

Performance
Peel Strength, g/in, 50 mm/min.
HDPE (4 mil)/ HDPE (4 mil)	5790	3970	2180	2720	6200	6265
Mylar(3 mil)/PP (120 mil)	10430	4770	2970	3400	12260	9530

[0026] The data in Table IV clearly shows that a highly significant increase in adhesion to both HDPE and PP surfaces is obtained even though the amounts of amorphous polypropylene, selectively hydrogenated block copolymer and tackifier are varied over a wide range.

[0027] Still another series of runs was made and the data obtained are set forth below in Table V.

TABLE V

Effect Of Tackifier Type On Blend Performance
RUN #	15	16	17	18	19	20	21	22	23	24
	PARTS BY WEIGHT, GRAMS
APP, K-TAC 100B	47.50	47.50	47.50	47.50	47.50	47.50	47.50	47.50	47.50	47.50
Kraton GX-1657	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00
Piccotac 95	47.50	-	-	-	-	-	-	-	-	-
Wingtac 10	-	47.50	-	-	-	-	-	-	-	-
Piccolyte A 115	-	-	47.50	-	-	-	-	-	-	-
Piccolyte S 115	-	-	-	47.50	-	-	-	-	-	-
Piccolyte S 10	-	-	-	-	47.50	-	-	-	-	-
Regalrez 1094	-	-	-	-	-	47.50	-	-	-	-
Regalite 7070	-	-	-	-	-	-	47.50	-	-	-
Foral AX	-	-	-	-	-	-	-	47.50	-	-
Foral B5	-	-	-	-	-	-	-	-	47.50	-
Escorez 5300	-	-	-	-	-	-	-	-	-	47.50
Isonox 129/ DLTDP (1:1)	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60
Total	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6

Properties
Viscosity,cps @ 350°F	1500	650	1700	2000	850	1550	1350	1050	1250	2500
R&B,°C	151	145	147	150	147	148	148	147	148	150

Performance
Peel Strength, g/in., 50mm/min.
HDPE(4 mil)/ HDPE(4 mil)	5450	910	5450	5450	1040	5450	5450	4448	5943	2450
Mylar (3 mil)/ PP (120 mil)	12710	1090	13170	14070	1410	13170	10900	6844	9662	7630

[0028] As seen from Table V, the adhesion obtained in each of Runs 15, 17, 18 and 20 to 24 is still extremely high when the amorphous polypropylene and the block copolymer are combined with a variety of tackifiers. Although in Runs Nos. 16 and 19, the adhesivity to HDPE and PP surfaces was low, about the same order as obtained in Runs Nos. 1 and 2, it should be pointed out that Runs Nos. 16 and 19 should be compared, however, with Run No. 8 in showing that the presence of all three components, namely, amorphous polypropylene, the block copolymer and a tackifier, must be present to obtain an improved adhesivity. For example when approximately equal amounts of amorphous polypropylene and a low softening point tackifier alone were used in the preparation of the adhesive in Run No. 8, adhesivity to both HDPE and PP surfaces was extremely low. When, however, in Runs 16 and 19, a small amount of the Kraton GX-1657 selectively hydrogenated block copolymer was added to approximately equal amounts of amorphous polypropylene and a low softening point tackifier, significantly improved adhesion to both HDPE and PP was achieved in comparison to Run No. 8.

[0029] Yet another series of runs was made. The data obtained are set forth below in Table VI.

TABLE VI

Effect Of Elastomer Type On Blend Performance
RUN #	25	26	27	28	29	30	31	32	33
	PARTS BY WEIGHT, GRAMS
APP, K-TAC 100B	-	-	-	-	60.10	47.50	47.50	60.10	50.00
APP, K-TAC 400	60.10	47.50	47.50	60.10	-	-	-	-	-
Kraton D-1107	13.30	-	-	-	-	-	-	-	-
Kraton D-1102	-	5.00	-	-	-	-	-	-	-
Kraton G-1650	-	-	5.00	-	-	-	-	-	-
Kraton G-1652	-	-	-	13.30	6.65	5.00	-	-	-
Kraton GX-1657	-	-	-	-	6.65	-	-	-	-
Kraton GX-1726	-	-	-	-	-	-	5.00	13.30	-
Kraton G-1701	-	-	-	-	-	-	-	-	15.00
Escorez 5380	26.60	47.50	47.50	26.60	26.60	47.50	47.50	26.60	35.00
Isonox 129/ DLTDP (1:1)	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60
Total	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6

Properties
Viscosity,cps @ 350°F	11250	4150	7625	34000	7500	1450	950	4500	26500
R&B,°C	153	150	153	157	153	144	150	152	151

Performance
Peel Strength, g/in., 50mm/min.
HDPE(4 mil)/ HDPE (4 mil)	1134	4876	5440	5217	5330	4083	4355	2540	1725
Mylar(3 mil)/ PP (120 mil)	340	No Ad	10206	6124	5443	6714	6079	3448	2590

[0030] The data in Table VI exemplify the critical need of combining the amorphous polypropylene and tackifier with a selectively hydrogenated alkenyl arene/conjugated diene block copolymer to obtain an adhesive having improved adhesivity to HDPE and PP surfaces. In each of Runs Nos. 25 and 26, wherein the midblock isoprene and butadiene polymers were not hydrogenated, poor results were obtained. However, in each of Runs Nos. 27 to 33, wherein various types of selectively hydrogenated elastomers of varying midblock characteristics, styrene levels and molecular weights were used, excellent adhesivities were obtained.

[0031] A further series of runs was made and the data obtained are set forth below in Table VII.

TABLE VII

Influence Of APP Type On Blend Performance
RUN #	34	35	36	37	38	39	40	41
	PARTS BY WEIGHT, GRAMS
APP, K-Tac 100	47.50	-	-	-	60.10	-	-	-
APP, K-Tac 100 A	-	47.50	-	-	-	60.10	-	-
APP, K-Tac 100D	-	-	47.50	-	-	-	60.10	-
APP, K-Tac 400	-	-	-	47.50	-	-	-	60.10
Kraton GX-1657	5.00	5.00	5.00	5.00	13.30	13.30	13.30	13.30
Escorez 5380	47.50	47.50	47.50	47.50	26.60	26.60	26.60	26.60
Isonox 129/ DLTDP (1:1)	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60
Total	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6

Properties
Viscosity,cps @ 350°F	600	1150	2525	5550	3000	5000	9875	24250
R & B,°C	143	140	146	152	135	148	152	157

Performance
Peel Strength, g/in., 50mm/min.
HDPE(4 mil)/ HDPE (4 mil)	5900	5680	5680	5444	4540	5220	5450	4430
Mylar(3 mil)/ PP (120 mil)	6810	7720	8170	11386	4990	4990	5220	6360

[0032] Runs Nos. 34 to 41 in Table VII show that excellent results are obtained herein using amorphous polypropylenes over a wide molecular weight range, that is, viscosity, while varying the amounts of the components used.

[0033] An additional series of runs was made. The data obtained are set forth below in Table VIII.

TABLE VIII

Influence Of Amorphous Polyalphaolefin Type On Blend Performance
RUN #	42	43	44	45	46	47	48	49	50
	PARTS BY WEIGHT, GRAMS
Vestoplast 508	47.50	-	-	-	-	-	-	-	47.50
Vestoplast 703	-	47.50	-	-	-	-	-	-	-
Vestoplast 608	-	-	47.50	-	-	-	-	-	-
Vestoplast V3643	-	-	-	47.50	-	-	-	-	-
Eastobond M-5H	-	-	-	-	47.50	-	-	-	-
Eastobond M-5C	-	-	-	-	-	47.50	-	-	-
Rextac B3815	-	-	-	-	-	-	47.50	-	-
Rextac B6835	-	-	-	-	-	-	-	47.50	-
Kraton G 1657	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00
Escorez 5380	47.50	47.50	47.50	47.50	47.50	47.50	47.50	47.50	-
Regalrez 1094	-	-	-	-	-	-	-	-	47.50
Isonox 129/ DLTDP (1:1)	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60	0.60
Total	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6	100.6

Properties
Viscosity,cps @ 350°F	4300	2050	4850	4050	2150	2750	1650	2850	3900
R & B,°C	95	63	145	109	142	98	132	116	84

Performance
Peel Strength, g/in., 50mm/min.
HDPE(4 mil)/ HDPE (4 mil)	4808	5715	4568	5262	5720	6360	4900	3630	6670
Mylar (3 mil)/ PP (120 mil)	7893	11680	8392	9072	8400	7720	7945	4540	11800

[0034] Runs Nos. 42 to 50 in Table VIII show that excellent results are obtained when the adhesive herein is prepared using various amorphous polyalphaolefins obtained from the polymerization of propylene with various other alpha olefins in place of amorphous polypropylene.

[0035] Obviously, many modifications and variations of the invention, as hereinabove set forth, can be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

Claims

1. A melt adhesive composition comprising an amorphous polypropylene, a selectively hydrogenated monoalkenyl arene/ conjugated diene block copolymer and a tackifier.

2. The melt adhesive composition of claim 1 wherein said amorphous polypropylene is obtained as a byproduct during the production of crystalline polypropylene.

3. The melt adhesive composition of claim 1 wherein said amorphous polypropylene is obtained as a direct product of the polymerization of propylene without the formation of crystalline polypropylene.

4. The melt adhesive composition of claim 1 wherein said amorphous polypropylene has a crystallinity of less than about 10 weight percent and a molecular weight in the range of about 300 to about 50,000.

5. The melt adhesive composition of claim 1 wherein said amorphous polypropylene has a crystallinity of less than about five weight percent and a molecular weight in the range of about 1000 to about 25,000.

6. The melt adhesive composition of claim 1 wherein said block copolymer contains the structure A-B, A-B-A₁ or (A-B)_xY, wherein A and A₁ are monoalkenyl arene polymer blocks, B is a block containing a hydrogenated conjugated diene polymer, Y represents a residue of a polyfunctional coupling agent or a polyfunctional initiator and x is a number having a value greater than 2.

7. The melt adhesive composition of claim 6 wherein said block copolymer contains the structure A-B.

8. The melt adhesive composition of claim 6 wherein said block copolymer contains the structure A-B-A₁.

9. The melt adhesive composition of claim 6 wherein said block copolymer contains the structure (A-B)_xY.

10. The melt adhesive composition of claim 6 wherein each of said block A, A₁ and B is substantially a homopolymer.

11. The melt adhesive composition of claim 6 wherein at least one of said blocks A and A₁ is a styrene polymer.

12. The melt adhesive composition of claim 6 wherein at least one of said blocks A and A₁ is an alpha methyl styrene polymer.

13. The melt adhesive composition of claim 6 wherein at least one of said blocks A and A₁ is a ring substituted styrene polymer.

14. The melt adhesive composition of claim 6 wherein at least one of said blocks A and A₁ is a ring alkylated styrene polymer.

15. The melt adhesive composition of claim 6 wherein said block B is an ethylene-butene-1 copolymer.

16. The melt adhesive composition of claim 6 wherein said block B is an ethylene-propylene copolymer.

17. The melt adhesive composition of claim 6 wherein said blocks A and A₁ are styrene polymers and B is an ethylene-butene-1 copolymer.

18. The melt adhesive composition of claim 6 wherein said blocks A and A₁ are styrene polymers and B is an ethylene-propylene.

19. The melt adhesive composition of claim 6 wherein the total average molecular weight range of the monoalkenyl arene polymer blocks is in the range of about 2000 to about 125,000.

20. The melt adhesive composition of claim 6 wherein the total average molecular weight range of the monoalkenyl arene polymer blocks is in the range of about 5000 to about 50,000.

21. The melt adhesive composition of claim 6 wherein the average molecular weight range of the selectively hydrogenated conjugated diene polymer block is in the range of about 10,000 to about 500,000.

22. The melt adhesive composition of claim 6 wherein the average molecular weight range of the selectively hydrogenated conjugated diene polymer block is in the range of about 20,000 to about 300,000.

23. The melt adhesive composition of claim 6 wherein the total weight of the monoalkenyl arene block(s) is in the range of about five to about 50 weight percent.

24. The melt adhesive composition of claim 6 wherein the total weight of the monoalkenyl arene block(s) is in the range of about 10 to about 35 weight percent.

25. The melt adhesive composition of claim 1 wherein said hydrocarbon tackifier has a ring and ball softening point in the range of about 10^o to about 150^o.

26. The melt adhesive composition of claim 1 wherein said hydrocarbon tackifier has a ring and ball softening point in the range of about 25^o to about 125^o.

27. The melt adhesive composition of claim 1 wherein said amorphous polypropylene has a crystallinity of less than about 10 weight percent and a molecular weight in the range of about 300 to about 50,000, said block copolymers contains the structure A-B, A-B-A₁ or (A-B)_xY, wherein A and A₁ are monoalkenyl arene polymer blocks, B is a block containing a hydrogenated conjugated diene polymer, Y represents a residue of a polyfunctional coupling agent or a polyfunctional initiator and x is a number having a value greater than 2, the total average molecular weight of said monoalkenyl arene blocks being in the range of about 2000 to about 125,000 and the average molecular weight of said selectively hydrogenated conjugated diene polymer block being in the range of about 10,000 to about 500,000, with the total weight of the monoalkenyl arene blocks being in the range of about five to about 50 weight percent, and said hydrocarbon tackifier has a ring and ball softening point in the range of about 10^o to about 150^oC.

28. The melt adhesive composition of claim 27 wherein said amorphous polypropylene has a crystallinity of less than about five weight percent and a molecular weight in the range of about 1000 to about 25,000, the total average molecular weight of said monoalkenyl arene blocks are in the range of about 5000 to about 50,000, the average molecular weight of said selectively hydrogenated conjugated diene polymer block is in the range of about 20,000 to about 300,000, the total weight of the monoalkenyl arene blocks are in the range of about 10 to about 35 weight percent and said hydrocarbon tackifier has a ring and ball softening point in the range of about 25^o to about 125^oC.

29. The melt adhesive of claim 27 wherein said block copolymer contains the structure A-B.

30. The melt adhesive of claim 27 wherein said block copolymer contains the structure A-B-A₁.

31. The melt adhesive of claim 27 wherein said block copolymer contains the structure (A-B)_xY.

32. The melt adhesive of claim 28 wherein said block copolymer contains the structure A-B.

33. The melt adhesive of claim 28 wherein said block copolymer contains the structure A-B-A₁.

34. The melt adhesive of claim 28 wherein said block copolymer contains the structure (A-B)_xY.

35. The melt adhesive composition of claim 28 wherein said blocks A and A₁ are styrene polymers and said block B is an ethylene-butene-1 copolymer.

36. The melt adhesive composition of claim 28 wherein said blocks A and A₁ are styrene polymers and said block B is an ethylene-propylene copolymer.

37. The melt adhesive composition of claim 1 wherein said components are present in the following amounts:

	Weight Percent
Amorphous Polypropylene	5 - 95
Selectively Hydrogenated Block Copolymer	2.5 - 40
Hydrocarbon Tackifier	2.5 - 55

38. The melt adhesive composition of claim 1 wherein said components are present in the following amounts:

	Weight Percent
Amorphous Polypropylene	30 - 90
Selectively Hydrogenated Block Copolymer	5 - 20
Hydrocarbon Tackifier	5 - 50